From patchwork Mon Aug 30 13:25:24 2010
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Subject: [Ada] update stack realignment for foreign conventions
From: Olivier Hainque
X-Patchwork-Id: 63027
Message-Id: <20100830132523.GA13189@cardhu.act-europe.fr>
To: gcc-patches@gcc.gnu.org
Cc: hainque@adacore.com
Date: Mon, 30 Aug 2010 15:25:24 +0200
Stack realignment for Ada subprograms with foreign convention
(expected on the tiny case below) stopped working on x86 so time ago.
Indeed, it still relies on the definition of
FORCE_PREFERRED_STACK_BOUNDARY_IN_MAIN and things have changed in this area.
This patch fixes this by adjusting the control macros in accordance with
the current MAIN_STACK_BOUNDARY instead.
Fixes the tescase at hand. Bootstrapped and regtestsed on x86-suse-linux.
Olivier
2010-08-30 Olivier Hainque
* gcc-interface/decl.c (FOREIGN_FORCE_REALIGN_STACK): New macro,
replacement for FORCE_PREFERRED_STACK_BOUNDARY_IN_MAIN.
(gnat_to_gnu_entity) : Use it.
---
procedure P;
pragma Convention (C, P);
procedure P is
procedure process;
pragma import (c, process);
begin
process;
end;
Index: ada/gcc-interface/decl.c
===================================================================
--- ada/gcc-interface/decl.c (revision 163581)
+++ ada/gcc-interface/decl.c (working copy)
@@ -60,27 +60,20 @@
#define Has_Stdcall_Convention(E) (0)
#endif
-/* Stack realignment for functions with foreign conventions is provided on a
- per back-end basis now, as it is handled by the prologue expanders and not
- as part of the function's body any more. It might be requested by way of a
- dedicated function type attribute on the targets that support it.
+/* Stack realignment is necessary for functions with foreign conventions when
+ the ABI doesn't mandate as much as what the compiler assumes - that is, up
+ to PREFERRED_STACK_BOUNDARY.
- We need a way to avoid setting the attribute on the targets that don't
- support it and use FORCE_PREFERRED_STACK_BOUNDARY_IN_MAIN for this purpose.
+ Such realignment can be requested with a dedicated function type attribute
+ on the targets that support it. We define FOREIGN_FORCE_REALIGN_STACK to
+ characterize the situations where the attribute should be set. We rely on
+ compiler configuration settings for 'main' to decide. */
- It is defined on targets where the circuitry is available, and indicates
- whether the realignment is needed for 'main'. We use this to decide for
- foreign subprograms as well.
-
- It is not defined on targets where the circuitry is not implemented, and
- we just never set the attribute in these cases.
-
- Whether it is defined on all targets that would need it in theory is
- not entirely clear. We currently trust the base GCC settings for this
- purpose. */
-
-#ifndef FORCE_PREFERRED_STACK_BOUNDARY_IN_MAIN
-#define FORCE_PREFERRED_STACK_BOUNDARY_IN_MAIN 0
+#ifdef MAIN_STACK_BOUNDARY
+#define FOREIGN_FORCE_REALIGN_STACK \
+ (MAIN_STACK_BOUNDARY < PREFERRED_STACK_BOUNDARY)
+#else
+#define FOREIGN_FORCE_REALIGN_STACK 0
#endif
struct incomplete
@@ -4208,13 +4201,10 @@
get_identifier ("stdcall"), NULL_TREE,
gnat_entity);
- /* If we are on a target where stack realignment is needed for 'main'
- to honor GCC's implicit expectations (stack alignment greater than
- what the base ABI guarantees), ensure we do the same for foreign
- convention subprograms as they might be used as callbacks from code
- breaking such expectations. Note that this applies to task entry
- points in particular. */
- if (FORCE_PREFERRED_STACK_BOUNDARY_IN_MAIN
+ /* If we should request stack realignment for a foreign convention
+ subprogram, do so. Note that this applies to task entry points in
+ particular. */
+ if (FOREIGN_FORCE_REALIGN_STACK
&& Has_Foreign_Convention (gnat_entity))
prepend_one_attribute_to
(&attr_list, ATTR_MACHINE_ATTRIBUTE,